1. Field of the Invention
This invention relates to polyimide resin compositions. More particularly, it relates to polyimide resin compositions useful as semiconductor encapsulating material and also applicable as semiconductor package substrates and hybrid IC substrates.
2. Discussion of Prior Art
At present, IC, LSI and other semiconductor circuits are encapsulated with resinous sealants, typically epoxy resin-silica blends by transfer molding. With a rapidly increasing degree of integration of semiconductor circuit, the conventional epoxy-silica encapsulating compounds turn to be unsatisfactory because they have an increased coefficient of linear thermal expansion and are less heat resistant and less reliable.
There is a need for a resin based encapsulating compound having a higher heat resistance and a lower coefficient of linear expansion. In this respect, polyimide resins are promising resins.
In general, polyimide resins are less resistant to humidity. Polyimide resins are blended with inorganic fillers to form semiconductor encapsulating compounds which often fail to play the requisite role of imparting humidity resistance to semiconductor circuits. The polyimide resins are thus regarded unsuitable as encapsulating compound.
Tailored polyimide resins are known in the art, including reaction products from oligoimides and hydroxylic organic silicon compounds and reaction products from oligoimides, polyamines and hydroxylic organic silicon compounds as disclosed in Japanese Patent Application Kokai No. 54-138100 and 56-11926. Aging resistance is imparted to ordinary polyimide resins while maintaining their heat resistance.
In summary, conventional epoxy resin-silica blends have a high coefficient of linear expansion and are less heat resistant and less reliable, and conventional polyimide resins are less moisture-proof.